It's often better to avoid floating point values on embedded systems and in this case there is no reason to use float at all, we can just represent the value in millivolts. Therefore the formula can be simplified to: But we’re not here to talk about that today. Instead, we are here to talk about this super cheap brand that does not contain any real diamonds yet has the same style of a bust down watch. NOTE: The controller goes to sleep when no event is detected. In sleep mode, the controller does not communicate on the I²C bus (it appears disconnected). So, for the communication to work, you need to tap on the screen so that the chip wakes-up.

The measured voltage is actually half of the actual battery voltage, because the ADC is connected between a voltage divider where both resistors are 1MΩ. This can be corrected by multiplying the value:Other than that, though, these are sure to impress in party or club type settings. Now, we can talk about the prices. Pricing Enable the DC/DC regulator. This doesn't affect the current consumption while sleeping, but almost halves the runtime current consumption.

Reading the battery voltage is a bit harder. For that you can use the battery voltage pin on P0.31 (AIN7). The returned value is 12 bits, which means it is 0..4095. You can get the measured voltage with the following formula, assuming a reference voltage of 3.3V (this is configurable in the ADC): So, are Pintime watches really worth it? All things considered, you are looking at a watch that definitely doesn’t hold to the highest of quality standards. For what they are though, and for such a low price, they aren’t bad really. I can’t complain.Put the heart rate sensor in sleep mode by setting the PDRIVER (0x0C) register to 0, see the HRS3300 datasheet for details. XTX XT25F32B 32Mb(4MB) SPI NOR Flash (data sheets for this part are hard to find but it acts similar to other QuadSPI SPI NOR Flash such as Macronix 32Mb(4MB) SPI NOR Flash)